Mackerel is known to be a rich source of omega-3 family PUFAs. The acid value and conjugated dienoic acid value of mackerel, known as indices of oxidation, were determined. Fatty acids in both raw and broiled mackerels were analyzed by GC. PUFAs and saturated fatty acids were observed at a low level in broiled mackerel, possibly as a result of thermal degradation of the lipids. In addition, volatile components in mackerel extracted by solvent-assisted flavor evaporation were analyzed by GC-MS. In total, 38 volatile components were detected in raw mackerel, whereas 53 volatiles were found in broiled mackerel. Hydrocarbons and methyl- and/or ethyl-substituted benzenes were quantitatively dominant. Levels of aldehydes and alcohols were significantly enhanced in broiled mackerel, as was the level of benzothiazole, which possibly forms as a result of the condensation of thermal degradation products from amino acids and/or proteins, and lipids.